1. Field of the Invention
The present general inventive concept relates to an inkjet image forming apparatus, and more particularly, to a cleaning device to clean a nozzle surface of a printhead, a length of the nozzle surface corresponding to a width of a printing medium, and an inkjet image forming apparatus including the cleaning device.
2. Description of the Related Art
An inkjet printer is a device for producing images by ejecting ink droplets from a printhead (a shuttle type printhead) onto a printing medium. The printhead is disposed at a predetermined distance from the printing medium and reciprocates in a direction (a widthwise direction of the printing medium) perpendicular to the paper movement.
Recently, high-speed printing has been performed using a printhead (a line printing type printhead) having a nozzle unit of a length corresponding to a width of a printing medium, as an alternative to using a printhead which reciprocates in a widthwise direction of a printing medium. Such a line printing type printhead has a nozzle unit including a plurality of nozzles that eject ink. After the ink is ejected, droplets which have not been ejected onto the printing medium may remain around the nozzle unit. When the nozzle unit is exposed to air during a standby state, the ink droplets not ejected may dry, and air born particulates, such as fine dusts, may be accumulated on the nozzle unit. The dried ink or particulates alter the ejecting direction of ink, thereby deteriorating printing quality. Furthermore, the line printing type printhead has a larger surface area than that of the shuttle type printhead, and thus more ink droplets remain around the nozzle unit. To solve the above problems, an inkjet image forming apparatus that includes a cleaning device that wipes off ink remaining on the surface of the nozzle unit has been developed.
FIG. 1 is a diagram of a printhead 30 and a wiping blade 40 included in an ink cartridge 20 of a conventional inkjet image forming apparatus. FIG. 2 is a view illustrating an enlarged contact portion between the printhead 30 and the wiping blade 40 illustrated in FIG. 1.
Referring to FIGS. 1 and 2, the printhead 30 which includes a plurality of nozzles (not shown) ejecting ink droplets is disposed below an ink cartridge 20 mounted on a carrier 10. Ink droplets ejected from the nozzle unit or other particulates may be easily accumulated on a nozzle surface 32, and thus the nozzle surface 32 of the printhead 30 is required to be cleaned. To this end, the inkjet image forming apparatus includes the wiping blade 40 for cleaning the nozzle surface 32 of the printhead 30. The wiping blade 40 is supported by a holder 50 and installed to move forward and backward. When the wiping blade 40 moves in a direction A, indicated by arrow A in FIG. 1, a leading end of the wiping blade 40 touches the nozzle surface 32 of the printhead 30 while being slightly bent. The wiping blade 40 wipes off the ink or particulates accumulated on the nozzle surface 32 while continuously moving in the direction A and contacting the nozzle surface 32.
A nozzle unit of a line printing type printhead to be cleaned has a length corresponding to a width of a printing medium. Therefore, waste toner removed from a nozzle array by the wiping blade 40 contaminates another nozzle array. Consequently, printing quality is deteriorated.
Further, the nozzle surface 32 of the printhead 30 is generally coated with a hydrophobic layer 34 to prevent ink from staining the nozzle surface 32. However, as the wiping blade 40 repeatedly performs a cleaning operation on the nozzle surface 32 of the printhead 30, the hydrophobic layer 34 is worn down due to repeated friction, thereby losing hydrophobic properties thereof. In this case, the nozzle surface 32 of the printhead 30 is easily contaminated by waste ink, and thus the printing quality can be deteriorated. Consequently, the conventional wiping blade 40 wears down the hydrophobic layer 34, thereby reducing the durability of the hydrophobic layer 34. Such a problem can be solved by using a wiper of a roller type instead of the wiping blade 40.
Japanese Patent Laid-open Publication No. JP2002-240309 discloses a roller type wiper. Since the roller type wiper has a limited cleaning capacity, the cleaning performance is lowered in time, and hence the wiper should be replaced after printing a predetermined number of sheets of paper. To increase the life span of the wiper, the radius of a roller should be increased, but this is difficult to realize because of a limited installation space. Therefore, an improvement in the wiper is needed.